Image sensor with tolerance optimizing interconnects

ABSTRACT

Embodiments of a hybrid imaging sensor that optimizes a pixel array area on a substrate using a stacking scheme for placement of related circuitry with minimal vertical interconnects between stacked substrates and associated features are disclosed. Embodiments of maximized pixel array size/die size (area optimization) are disclosed, and an optimized imaging sensor providing improved image quality, improved functionality, and improved form factors for specific applications common to the industry of digital imaging are also disclosed. Embodiments of the above may include systems, methods and processes for staggering ADC or column circuit bumps in a column or sub-column hybrid image sensor using vertical interconnects are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of: (1) U.S. Provisional ApplicationNo. 61/485,426, filed May 12, 2011; (2) U.S. Provisional Application No.61/485,432, filed May 12, 2011; (3) U.S. Provisional Application No.61/485,435, filed May 12, 2011; and, (4) U.S. Provisional ApplicationNo. 61/485,440, filed May 12, 2011, which are all hereby incorporated byreference herein in their entireties, including but not limited to thoseportions that specifically appear hereinafter, the incorporation byreference being made with the following exception: In the event that anyportion of the above-referenced. provisional applications areinconsistent with this application, this application supersedes saidabove-referenced provisional applications.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND

The disclosure relates generally to electromagnetic sensing and sensorsand also relates to low energy electromagnetic input conditions as wellas low energy electromagnetic throughput conditions. The disclosurerelates more particularly, but not necessarily entirely, to optimizingthe tolerances desired for using a stacking scheme for a hybrid imagesensor with minimal vertical interconnects between substrates andassociated systems, methods and features.

There has been a popularization of the number of electronic devices thatutilize and include the use of imaging/camera technology in general. Forexample, smartphones, tablet computers, and other handheld computingdevices all include and utilize imaging/camera technology. The use ofimaging/camera technology is not limited to the consumer electronicsindustry. Various other fields of use also utilize imaging/cameratechnology, including various industrial applications, medicalapplications, home and business security/surveillance applications, andmany more. In fact, imaging/camera technology is utilized in nearly allindustries.

Due to such popularization, the demand for smaller and smaller highdefinition imaging sensors has increased dramatically in themarketplace. High resolution and high definition means that more dataand must be moved in a relatively smaller space. The device, system andmethods of the disclosure may be utilized in any imaging applicationwhere size and form factor are considerations. Several different typesof imaging sensors may be utilized by the disclosure, such as acharged-couple device (CCD), or a complementary metal-oxidesemiconductor (CMOS), or any other image sensor currently known or thatmay become known in the future.

CMOS image sensors typically mount the entire pixel array and relatedcircuitry, such as analog-digital converters and/or amplifiers, on asingle chip. The size limitations of a CMOS image sensor often requirethat increasing more data is being moved within increasingly smallerconfines. The contact pads between circuits can be manufactured smallerand smaller between the sensor and other important functions, such assignal processing, due to the number of considerations that must beaccounted for in the design and manufacture of a CMOS image sensor.Thus, for example, increasing the pixel array area may come with atrade-off in other areas, such as A/D conversion or other signalprocessing functions, because of the decreased area in which the relatedcircuitry may occupy.

The disclosure optimizes and maximizes the pixel array withoutsacrificing quality of the signal processing by optimizing andmaximizing the pixel array on a first substrate and stacking relatedcircuitry on subsequent substrates. The disclosure utilizes advancementsin back-side illumination and other areas to take advantage ofoptimizing the area of the pixel array on a substrate. The stackingscheme and structure allow highly functional, large-scale circuits to beutilized while maintaining a small chip size.

The features and advantages of the disclosure will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by the practice of the disclosure withoutundue experimentation. The features and advantages of the disclosure maybe realized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the disclosure will become apparent froma consideration of the subsequent detailed description presented inconnection with the accompanying drawings in which:

FIG. 1 a is a schematic view of an embodiment of an imaging sensorconstructed on a single substrate;

FIG. 1 b is a schematic view of an embodiment of an imaging sensor,demonstrating the remote placement of processing circuits relative to apixel array in accordance with the teachings and principles of thedisclosure;

FIG. 2 illustrates a schematic view of an embodiment of an imagingsensor built on a plurality of substrates in accordance with theteachings and principles of the disclosure;

FIG. 3 a illustrates a perspective view of an embodiment of an imagingsensor made on a monolithic and illustrating a plurality of columnscomprising pixels and supporting circuitry, where the supportingcircuitry is one pixel in width;

FIG. 3 b illustrates a top view of an embodiment of an imaging sensormade on a monolithic and illustrating a plurality of columns comprisingpixels and supporting circuitry, where the supporting circuitry is onepixel in width;

FIG. 3 c illustrates a perspective view of a single column comprisingpixels and supporting circuitry taken from FIG. 3 a;

FIG. 3 d illustrates a top view of a single column comprising pixels andsupporting circuitry taken from FIG. 3 b;

FIG. 3 e illustrates a perspective view of an embodiment of an imagingsensor made on a monolithic and illustrating a plurality of columnscomprising pixels and supporting circuitry, where the supportingcircuitry is two pixels in width;

FIG. 3 f illustrates a top view of an embodiment of an imaging sensormade on a monolithic and illustrating a plurality of columns comprisingpixels and supporting circuitry, where the supporting circuitry is twopixels in width;

FIG. 3 g illustrates a perspective view of an embodiment of an imagingsensor built on a plurality of substrates with a pixel array on thefirst substrate and supporting circuitry located on a second orsubsequent substrate with interconnects and vias being shown connectingthe plurality of substrates in accordance with the teachings andprinciples of the disclosure;

FIG. 3 h illustrates a front view of the embodiment of an imaging sensorbuilt on a plurality of substrates of FIG. 3 g;

FIG. 3 i illustrates a perspective view of an embodiment of an imagingsensor built on a plurality of substrates wherein a plurality of pixelcolumns forming the pixel array are located on the first substrate and aplurality of circuit columns are located on a second substrate andshowing an electrical connection and communication between one column ofpixels to its associated or corresponding column of circuitry;

FIG. 3 j illustrates a perspective view of a single column of pixels anda single column of circuitry taken from FIG. 3 i showing an electricalconnection therebetween;

FIG. 3 k illustrates a front view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 i and 3 j showing anelectrical connection therebetween;

FIG. 3 l illustrates a side view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 i and 3 j showing anelectrical connection therebetween;

FIG. 3 m illustrates a perspective view of an embodiment of an imagingsensor built on a plurality of substrates wherein a plurality of pixelcolumns forming the pixel array are located on the first substrate and aplurality of circuit columns are located on a second substrate andshowing a plurality of electrical connections and communication betweenthe plurality of pixel columns and associated or corresponding columnsof circuitry;

FIG. 3 n illustrates a perspective view of an embodiment of an imagingsensor built on a plurality of substrates wherein a plurality of pixelcolumns forming the pixel array are located on the first substrate and aplurality of circuit columns are located on a second substrate, whereinthe circuit columns are two pixels in width and half of the length ofthe pixel column, and showing a plurality of electrical connections andcommunication between the plurality of pixel columns and associated orcorresponding columns of circuitry;

FIG. 3 o illustrates a perspective view of a single column of pixels anda single column of circuitry taken from the right most column of FIG. 3n showing an electrical connection therebetween;

FIG. 3 p illustrates a front view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 n and 3 o showing anelectrical connection therebetween;

FIG. 3 q illustrates a side view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 n and 3 o showing anelectrical connection therebetween;

FIG. 3 r illustrates a perspective view of a single column of pixels anda single column of circuitry taken from the left most column of FIG. 3 nshowing an electrical connection therebetween;

FIG. 3 s illustrates a front view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 n and 3 r showing anelectrical connection therebetween;

FIG. 3 t illustrates a side view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 n and 3 r showing anelectrical connection therebetween;

FIG. 3 u illustrates a perspective view of an embodiment of an imagingsensor built on a plurality of substrates wherein a plurality of pixelcolumns forming the pixel array are located on the first substrate and aplurality of circuit columns are located on a second substrate, whereinthe circuit columns are four pixels in width, and showing a plurality ofelectrical connections and communication between the plurality of pixelcolumns and associated or corresponding columns of circuitry;

FIG. 3 v illustrates a perspective view of a single column of pixels anda single column of circuitry taken from the right most column of FIG. 3u showing an electrical connection therebetween;

FIG. 3 w illustrates a front view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 u and 3 v showing anelectrical connection therebetween;

FIG. 3 x illustrates a side view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 u and 3 v showing anelectrical connection therebetween;

FIG. 3 y illustrates a perspective view of a single column of pixels anda single column of circuitry taken from the column to the left ofadjacent to the right most column of FIG. 3 u showing an electricalconnection therebetween;

FIG. 3 z illustrates a front view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 u and 3 y showing anelectrical connection therebetween;

FIG. 3 aa illustrates a side view of the single column of pixels and thesingle column of circuitry taken from FIGS. 3 u and 3 y showing anelectrical connection therebetween;

FIG. 4 illustrates an embodiment of an imaging sensor built on aplurality of substrates and also illustrating an embodiment of thespecific placement of support circuits in accordance with the teachingsand principles of the disclosure;

FIG. 5 illustrates an embodiment of an imaging sensor built on aplurality of substrates and also illustrating an embodiment of thespecific placement of support circuits wherein some of the circuits arerelatively remotely placed in accordance with the teachings andprinciples of the disclosure;

FIG. 6 illustrates an embodiment of a first substrate having variouspercentages of coverage by differing pixel arrays in accordance with theteachings and principles of the disclosure;

FIG. 7 illustrates an embodiment having a plurality of pixel arrays inaccordance with the teachings and principles of the disclosure;

FIG. 8 illustrates an embodiment of an image sensor with an optimizedpixel array and related or supporting circuitry being stacked andillustrating a light source in accordance with the teachings andprinciples of the disclosure;

FIG. 9 illustrates a backside illuminated embodiment of an image sensorwith an optimized pixel array and related or supporting circuitry beingstacked in accordance with the teachings and principles of thedisclosure;

FIG. 10 illustrates an embodiment of an image sensor wherein the pixelarray is more remotely located from all said supporting circuits inaccordance with the teachings and principles of the disclosure;

FIG. 11 illustrates an embodiment of an image sensor having stackedsubstrates of differing size in accordance with the teachings andprinciples of the disclosure;

FIG. 12 illustrates an embodiment of pixel architecture, where eachpixel column does not share a read bus with another pixel column;

FIG. 13 illustrates an embodiment of pixel architecture, where there isa horizontal 2-way share of pixel columns with respect to a read bus,such that there is one read bus per two pixel columns;

FIG. 14 illustrates an embodiment of an imaging sensor built on aplurality of substrates having a front illuminated pixel array inaccordance with the teachings and principles of the disclosure;

FIG. 15 illustrates an embodiment of an imaging sensor having pixelarray divided into read areas containing a plurality of pixels;

FIG. 16 illustrates an embodiment of an imaging sensor having aplurality of substrates and the connection of a plurality of buses foraccessing data from a pixel array divided into read areas containing aplurality of pixels;

FIG. 17 a illustrates an embodiment of a pixel array whereininterconnects are spaced relative to pixels within the pixel array inaccordance with the teachings and principles of the disclosure;

FIG. 17 b illustrates an embodiment of a pixel array whereininterconnects are spaced relative to columns within the pixel array inaccordance with the teachings and principles of the disclosure;

FIG. 17 c illustrates an embodiment of a pixel array wherein ainterconnects are spaced relative to areas within the pixel array inaccordance with the teachings and principles of the disclosure;

FIGS. 18 a-18 f illustrate embodiments of a pixel array, whereininterconnects may be spaced relative to defined pixel areas within thepixel array in accordance with the teachings and principles of thedisclosure;

FIG. 19 illustrates a method of spacing interconnects/bumps inaccordance with the principles and teachings of the disclosure;

FIG. 20 illustrates an embodiment wherein pixel area dedicated supportcircuits may be used such that each pixel area may have at least asupport circuit dedicated to processing only the data produced by pixelswithin the pixel area to which it is dedicated;

FIG. 21 illustrates an embodiment of a schematically large image sensorshowing the scalability of the principles and teaching of thedisclosure; and

FIG. 22 illustrates an embodiment of a schematically large image sensorshowing the scalability of the principles and teaching of thedisclosure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the disclosure claimed.

Before the devices, systems, methods and processes for staggering ADC orcolumn circuit bumps in a column or sub-column hybrid image sensor usingvertical interconnects are disclosed and described, it is to beunderstood that this disclosure is not limited to the particularstructures, configurations, process steps, and materials disclosedherein as such structures, configurations, process steps, and materialsmay vary somewhat. It is also to be understood that the terminologyemployed herein is used for the purpose of describing particularembodiments only and is not intended to be limiting since the scope ofthe disclosure will be limited only by the appended claims andequivalents thereof.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise.

In describing and claiming the subject matter of the disclosure, thefollowing terminology will be used in accordance with the definitionsset out below.

As used herein, the terms “comprising,” “including,” “containing,”“characterized by,” and grammatical equivalents thereof are inclusive oropen-ended terms that do not exclude additional, unrecited elements ormethod steps.

As used herein, the phrase “consisting of” and grammatical equivalentsthereof exclude any element or step not specified in the claim.

As used herein, the phrase “consisting essentially of” and grammaticalequivalents thereof limit the scope of a claim to the specifiedmaterials or steps and those that do not materially affect the basic andnovel characteristic or characteristics of the claimed disclosure.

As used herein, the term “proximal” shall refer broadly to the conceptof a portion nearest an origin.

As used herein, the term “distal” shall generally refer to the oppositeof proximal, and thus to the concept of a portion farther from anorigin, or a furthest portion, depending upon the context.

Digital imaging, whether still or movie, has many constraints placedupon it with regard to the devices used to record the image data. Asdiscussed herein, an imaging sensor may include a pixel array andsupporting circuits that are disposed on at least one substrate. Devicesusually have practical and optimal constraints on the form factor of theimaging sensor depending upon the application. With most applications,especially for commercial use, size is usually a constraint. Even inouter space applications where size would seemingly be the leastconstrained, size is still an issue because the imaging device needs tobe orbitally launched and overcome the force of gravity. Additionally,and especially in consumer electronics, any bulk added by the imagingdevice/camera takes away from possible other functional hardware orbattery capacity/life. Thus, size is nearly always a constraint thatmust be addressed in any application using an imaging sensor.

In many cases, the form factor of an imaging device is constrained.There may be unlimited area or real estate laterally/horizontally,relative to the pixel array, or there may be an abundance of spacedirectly behind a pixel array vertically. Often it is not the pixelarray that is the only consideration for fitment, but it is thesupporting circuitry that needs to be accommodated. The supportingcircuits may be, but are not necessarily limited to, analog to digitalconverters, power circuits, power harvesters, amplifier circuits,dedicated signal processors and filters, serializers for datatransmission, etc. In addition to circuits, physical property elementsmay be required, such as light filters and lenses. All of the above mustbe considered when deciding on and designing the form factor of animaging device and traditionally the industry has chosen lateral orhorizontal placement of supporting circuits when designing the imagesensors of the day. Yet, there are many applications that would benefitfrom a more vertical rather than lateral or horizontal form factor.

An example of an application that would benefit from an imaging devicehaving a relatively vertical (relative to the pixel array) form factorwould be in the fields of use requiring the use of a scope. For example,industrial scopes and medical endoscopes would benefit from an imagesensor that could be housed within a lumen of the device. In such ascope application, an image sensor that could be disposed in the lumenof the scope may be advantageous. The inside diameter (if round) of thelumen would then define maximum diameter (round) of the image sensor.With a popular lumen size range of 3 mm to 15 mm, it will be appreciatedthat the image sensor will be greatly limited in form factorconsiderations in the lateral direction due to the inside diameterconstraints. Accordingly, a more vertical configuration may beadvantageous.

Although size is an issue as stated above, pixel count numbers continueto climb industry wide no matter the specific application, and ofteneclipse the mediums that are used to actually view the images after theyhave been recorded, such as a computer monitor or television. However,it should be understood that all pixels are not created equal. In theexample above, a scope configuration may be used in a limited lightapplication. As such, a scope based image sensor that functions well inlow light situations may be advantageous. Large pixels have the abilityto collect more light than small pixels simply because of theirdifferent sizes. However, the trend in the marketplace has been toincrease the number of pixels in a given form factor. Logically morepixels in a given area generally mean smaller pixel size. Smaller pixelshave the shortfalls of not working well in lower light and creatingnoise because of the electronic crowding. Additionally, more pixelsequates to more boundary space relative to light gathering space. Largerpixels tend to produce better images and higher image quality becausethey simply have a larger ratio of light sensing portion to borderportion. Both of those issues lend to the poor image quality of todaysmall image sensors.

As pixel counts continue to grow in a given space pixel pitch decreasesthereby requiring greater precision for interconnect electrical contact.Accordingly, the cost of image sensor production can increase as theneed for greater precision in data handling is required for theincreased pixel pitch. Current technologies may be used to achieve imagesensors with increased capabilities but at increased cost as yields fallduring manufacture.

The techniques and structures disclosed herein with respect to a ratioof the pixel pitch to bump pitch will allow for the following:

-   -   Improved manufacturing reliability due to increased ability to        provided alternate interconnects, i.e., interconnect redundancy;    -   Maximize bump pitch size in a cost effective manner per        application or field of use;    -   Allows for more economical CMOS process due to the ability to        use larger pixel pitch;    -   Allows for more efficient bump technology access, i.e., read        data from multiple buses or directly off of a pixel array;    -   Allows for redundancy in CMOS process to improve yield;    -   Use of localized ADC in a pre-determined or defined pixel area;        and    -   Allows for multiple pixel array geometries, plurality of buses,        and column bump configurations to be utilized.

The above-identified issues describe the current state of the artrelative to a few needs within the industry. What is needed is an imagesensor having adequate resolution by way of pixel count, a verticalarchitecture and form factor, and as large as possible pixel size, allwhile constrained in a limited space. The disclosure contemplates andwill discuss embodiments and methods of design that address these andpotentially other issues by optimizing the size of the pixel array on asubstrate/chip and remotely locating supporting circuits in a generallyvertical configuration on one or more supporting substrates/chips.

High performance image sensors that use on-chip analog to digitalconverters (ADC), on-chip digital and analog algorithms, on-chip complextimings, and on-chip complex analog functions provide high qualityimages because of the following reasons (the list below is not acomplete list, but is given merely for exemplary purposes):

No pick-up noise due to long off-chip analog data lines (if no on-chipADC, then analog signals need to be sent off-chip);

Lower temporal noise because digital conversion is carried out early inthe data path (no extra amplifier, buffer that will add extra noise);

Local timing optimization using complex on-chip timing generator.Because of pad count limitation, only simple timing can be performed,using external system;

Lower noise generated by I/O. On-chip systems allow for reduced padcount; and

Faster operation can be achieved (more serial on-chip operation, reducedstray capacitances and resistances).

However the elaborated functions and processes used to provide such highquality images occupy a very large area around the pixel array andsignificantly lower the ratio of the pixel array size to die size. It iscommon to have a ratio of pixel array size to die size below 25% in animaging system that uses on-chip processes and circuitry, including ADCsand the other elaborated functions noted above. Thus, there is atrade-off between ratio of pixel array size to die size and on-chipfunctions.

Therefore, most of the applications of the technology that need to usean optimized ratio of pixel array size to die size use customized imagesensors without digital conversion (analog out) or with reducedanalog/digital functionality and lower grade analog to digitalconversion. Even in that case, the ratios of pixel array size to diesize that are greater than 50% are difficult to achieve.

The disclosure demonstrates and contemplates a system and method ofincreasing the ratio of pixel array size to die size without sacrificingimage quality. The disclosure contemplates imaging applications using agiven die size and where maximized pixel array size is required orimaging applications using a given pixel array size, but where smallerdie size is required.

One of the key issues of the three dimensional stacking technology isthe bump pitch. Current technologies achieve a bump pitch of around 50μm to 100 μm. In the next three to ten years, it is expected thatdeveloping technologies will permit the bump pitch to be decreased, insize in a range that is equal or nearly the same size as pixel pitch.

Moreover stacked substrates/chips yield depends directly upon the bumppitch. The most frequent failure in stacked substrates/chips is anelectrical short between two interconnects or bumps. As bump pitchdecreases in size and becomes smaller, the planarization specificationof the wafers has to be tighter. In order to absorb the waferplanarization errors, the interconnects or bumps are made or growntaller. However, excess metal in taller interconnects/bumps tends tomove to the side(s) during the wafer bonding process, which may shortneighboring or adjacent bumps. Higher yield and lower costs due to arelaxed wafer alignment process can be achieved by relaxing theinterconnect or bump pitch.

The disclosure proposes a device, system, method of relaxing the bumppitch while working on a tighter pixel pitch.

The disclosure also contemplates an image sensor that might otherwise bemanufactured with its pixel array and supporting circuitry on a single,monolithic substrate/chip and separating the pixel array from all or amajority of the supporting circuitry. The disclosure may use at leasttwo substrates/chips, which will be stacked together usingthree-dimensional stacking technology. The first of the twosubstrates/chips may be processed using an image CMOS process. The firstsubstrate/chip may be comprised either of a pixel array exclusively or apixel array surrounded by limited circuitry. The second or subsequentsubstrate/chip may be processed using any process, and does not have tobe from an image CMOS process. The second substrate/chip may be, but isnot limited to, a highly dense digital process in order to integrate avariety and number of functions in a very limited space or area on thesubstrate/chip, or a mixed-mode or analog process in order to integratefor example precise analog functions, or a RF process in order toimplement wireless capability, or MEMS (Micro-Electro-MechanicalSystems) in order to integrate MEMS devices. The image CMOSsubstrate/chip may be stacked with the second or subsequentsubstrate/chip using any three-dimensional technique. The secondsubstrate/chip may support most, or a majority, of the circuitry thatwould have otherwise been implemented in the first image CMOS chip (ifimplemented on a monolithic substrate/chip) as peripheral circuits andtherefore have increased the overall system area while keeping the pixelarray size constant and optimized to the fullest extent possible. Theelectrical connection between the two substrates/chips may be donethrough interconnects, which may be wirebonds, μbump and/or TSV (ThroughSilicon Via).

Referring now to FIG. 1 a and 1 b, FIG. 1 a an example of an imagingsensor of monolithic design wherein a single substrate is used as thebasis of chip construction. As can be seen in FIG. 1 a, a substrate 100a may comprise a pixel array 150 a that is configured to receiveelectromagnetic energy, convert it to data, and then pass that data onto supporting circuits 110 a, 120 a, 130 a for processing that willultimately result in a digital image or video. The supporting circuitsmay include signal processing circuits such analog to digital converters110 a, amplifier circuits 130 a, filter circuits, power supplying andharvesting circuits 120 a, and serial processors to name only a few.Some of the supporting circuits may be located nearer to the pixel arraythan other circuits and connected to each pixel of the pixel array viabuses. For example, amplification circuits and digital conversioncircuits may be preferred to be located closer to the pixel arraybecause that architecture may increase the clarity of the data streamand introduce minimal noise to the system. As can be seen in FIG. 1 a,image sensor 100 a is a schematic illustration of what is typicallyavailable in the marketplace with regard to image sensors. FIG. 1 aillustrates a generally lateral placement of the supporting circuitsrelative to the pixel array 150 a, which dominates the marketplace todaybecause of cost and manufacture limitations. Lateral placement of thesupporting circuits on the same substrate as, and with respect to, thepixel array 150 a simplifies the architecture and reduces the cost ofproduction. However, the use of a single substrate has some drawbacksand limitations, such as form factor issues, because not allapplications lend themselves to a lateral or horizontal circuitplacement as discussed above. As is illustrated in FIG. 1 b, when thesupport circuits, such as 110 a, 120 a, 130 a, are removed from thefirst substrate 160 there remains considerable room for a larger pixelarray 150 a to be located on the first substrate 160, which means moreor larger pixels can be used. Given the same physical limitations in anelectronic device using an imaging sensor, using the techniques andcombination of features disclosed herein allows either increased pixelresolution or increased pixel size to be used. In such cases, the imagesensor substrates can be reduced in size and used in more devices wheresize is of primary concern and yet a high quality image is desired.Specifically, the figure (1 b) illustrates the design concept ofremotely locating support circuits 110 b, 120 b and 130 b relative tothe pixel array.

Referring primarily to FIG. 2, the use of supporting substrates to carrysupporting circuits will be discussed. In an embodiment of an exemplaryimage sensor 200, a pixel array 205, which may comprise a plurality ofpixels that are formed into a plurality of pixel columns, are positionedon a surface of a first substrate 210. Each of the plurality of pixelcolumns located on the first substrate 210 may be electrically connectedto a read bus 240. Signal processing and image enhancement may beperformed by supporting circuits located on a second substrate 220. Thecircuits may include signal processing circuits, such as analog todigital converters 228, amplifier circuits 226, filter circuits 224,power supplying and harvesting circuits 222, which may be formed into aplurality of circuit columns that correspond with the plurality of pixelcolumns on the first substrate 210. Each circuit column may be comprisedof a plurality of supporting circuits that is in electroniccommunication with a read bus 230 or plurality of read busescorresponding to each circuit column. In other words, the signalprocessing circuits may be located on a second substrate or supportingsubstrate 220. Each of the plurality of circuit columns on the secondsubstrate 220 may then be electronically connected to a correspondingpixel column located on the first substrate 210 through an interconnect,such as a solder bump, solder ball or via, which may be located anywherealong the physical path where the read buses 230, 240 are superimposedor overlap. It is also within the scope of this disclosure tocontemplate the use of a plurality of secondary substrates, eachsubstrate housing any needed circuits for an image sensor and in anyorder or combination of supporting circuits depending upon the desiredfunction of the image sensor.

As illustrated in FIGS. 3 a through 3 f, an image sensor 300 a maygenerally comprise a pixel array 350 a and supporting circuitry 370 a,which may comprise an analog to digital converter 317 a, an amplifier315 a, a filter 314 a and a clock 316 a all of which may be disposed ona monolithic substrate 310 a. In FIGS. 3 a and 3 b, a monolithic imagesensor is illustrated in a perspective view and a top view,respectively. The pixel array 350 a may be comprised of a plurality ofpixel columns, wherein each of the plurality of pixel columns 352 acomprises a plurality of individual pixels. The supporting circuitry 370a may comprise a plurality of circuit columns 356 a, wherein each of thecircuit columns 356 a comprises circuitry to support a correspondingpixel column 352 a. As illustrated in the figures, the monolithiccircuit columns 356 a are each one pixel in width and are locallylocated relative to a pixel column to which they correspond. The figuresillustrate a pixel array of unshared pixels with one read bus per pixelcolumn electrically connected to the corresponding column circuitry onone side of the image sensor only. It will be appreciated that thecorresponding circuitry is one pixel wide in the embodiment, however,other configurations of support circuitry as discussed below arecontemplated within the scope of this disclosure and may be used toincrease the image sensor design options.

Referring now to FIGS. 3 c and 3 d, a single pixel column 352 acomprising a plurality of pixels and a single circuit column 356 a areillustrated in a perspective view and a top view, respectively. It willbe appreciated that the single pixel column 352 a and the correspondingcircuit column 356 a illustrated in the figures are taken from the imagesensor 300 a illustrated in FIGS. 3 a and 3 b and simply denote a singlepixel column 352 a electrically connected to a single circuit column 356a.

FIGS. 3 e and 3 f illustrate a perspective view and a top view of anembodiment of an imaging sensor 300 a made on a monolithic substrate andillustrating a plurality of columns comprising pixels and supportingcircuitry. In contrast to FIGS. 3 a and 3 b, FIGS. 3 e and 3 fillustrate the supporting circuitry as being two pixels in width. In thefigures it can be seen that alternating pixel columns 352 a read tocorresponding circuitry located at opposing ends of the pixel columns352 a. Such a configuration offers variations in aspect ratios ofcorresponding circuit column 356 a areas. Because the buses 330 a readto alternating ends of the pixel array 350 a, the circuit column 356 acan be two pixels wide. Contrasting the sensors illustrated in FIGS. 3 band 3 f, the pixel column 352 a illustrated in FIG. 3 b has an aspectratio of six pixels (units) long by one pixel wide (6/1) and the circuitcolumn 356 a has a similar aspect ratio. Conversely, the image sensorillustrated in FIG. 3 f has a pixel column 352 a that has an aspectratio of six pixels (units) long by one pixel wide (6/1) and the circuitcolumn 356 a has an aspect ratio of two pixels wide and three pixelslong (2/3).

In contrast, the same functionality of an imaging sensor 300 a built ona monolithic substrate (shown in FIGS. 3 a-3 f) can be provided andsupplied in an imaging sensor 300 that has a much smaller dimension (inat least the lateral direction and having a much smaller area and formfactor) than a monolithic substrate or chip. Referring now to FIGS. 3 gthrough 3 aa, an imaging sensor 300 will be discussed that may comprisea pixel array 350 that may be disposed on a first substrate 310, whileall of the supporting circuits 370 may be remotely located (with respectto the pixel array 350 and first substrate 310) to one or moresupporting substrates, such as a second, substrate 311 and a thirdsubstrate 312.

It should be noted that the image sensor may be built and manufacturedon a plurality of substrates. Each of the plurality of substrates may belocated with respect to each other in a stacked configuration orformation, where all of the supporting substrates are stacked or alignedbehind the first substrate 310, which comprises the pixel array 350, andrelative to an object to be imaged. Each of the substrates in the stackmay be electrically connected through interconnects 321, such as solderbumps or solder balls, vias or other forms of electrical communication.It will be appreciated that the interconnects 321 may include any knownmeans or method for conducting electrical signals to various circuits onthe same or different substrates without departing from the scope of thedisclosure.

In FIGS. 3 g, 3 i, 3 m, 3 n, and 3 u, each of the plurality ofsubstrates comprising the pixel array 350 and the various supportingcircuits 370 of the image sensor 300 may be of similar size in thestack, such that the plurality of substrates may be substantiallyaligned within the stack. In an embodiment, the first substrate 310 andthe plurality of subsequent supporting substrates 311 may be stacked insubstantial alignment so that a plurality of communication columns areformed in a multi-layer stack of substantially the same length andwidth.

It should be noted that in other embodiments, where the form factor willallow it, different sized substrates having different lengths and widthsmay be used and may be preferred in the stack. Considerations such asheat dissipation and noise, along with many more considerations, may beaccounted for when designing a stacked configuration. For example, in anembodiment, a high heat circuit, such as an amplifying circuit, may beplaced on a protruding portion of one of the supporting substrateswithin a stack (illustrated best in FIG. 11).

It should be noted that a pixel array 350 may be formed in a pluralityof rows of pixels and a plurality of columns of pixels. Each pixelcolumn 352 may comprise a plurality of pixels in a linear form factor,which is one pixel wide and “N” pixels long. It should be further notedthat each pixel column 352 will have an area value that is generally aswide as the pixel pitch and as long as is predetermined by sensordesign.

Conversely, a circuit column 356, as referred to herein, is an allocatedspace on a substrate, other than a first substrate 310 comprising thepixel array 350, which comprises at least one support circuit 370 thatis dedicated and electrically connected, to, or in electricalcommunication with, a corresponding pixel column 352. It will beappreciated that the space occupied by the pixel column 352 may be thesame as, or substantially the same as, the space occupied by the circuitcolumn 356 that corresponds with that pixel column 352. Thus, the secondor supporting substrate 311 may comprise a plurality of circuit columns356, wherein each circuit column 356 comprises substantially the same orsimilar real estate area on the second substrate 311 as a correspondingpixel column 352 has area on the first substrate 310.

Additionally, each pixel column 352 is or may be in electroniccommunication with a read bus 330 on the first substrate 310, while thecircuit column 356 is or may be in electronic communication with a readbus 340 on the second substrate 311. The two aforementioned buses 330,340 may be electrically connected by at least one interconnect 321 thatis located anywhere along the path created by, or within, thesuperimposition of or between the two buses 330, 340 as illustrated inFIGS. 3 g through 3 aa. In an embodiment, a plurality of interconnects321 may be used to connect a single pixel column 352 to a singlecorresponding circuit column 356. In such an embodiment, the redundancyin the number of interconnects 321 used may provide for increasedproduction yield or increased functionality.

As referred to herein, aspect ratio will be used to refer to the generalshape of an area on a substrate. For example, an area defined as being 4pixel units wide and 5 pixel units long will have an aspect ratio of 4/5or 5/4. The term aspect ratio may be used generically to denote asituation where the shape of an area is considered important. Forexample, the concept of aspect ratio may be used to denote differencesin the aspect ratios of two corresponding areas that are located ondiffering substrates. It should be noted that the aspect ratios of thepixel columns 352 and the circuit columns 356 illustrated in FIGS. 3 g-3aa may be the same or may be different, the area of the footprint of thepixel column 352 and its corresponding circuit column 356 may besubstantially the same or equal. Several examples of different aspectratios are illustrated in FIGS. 3 g through 3 aa, but it should be notedthat the principles of this disclosure may be applied to any number ofaspect ratio configurations. However, as illustrated in the figures, thearea of the circuit column 356 footprint or real estate is substantiallythe same as or equal to the area of the footprint or real estate of thepixel column 352. As manufacturing techniques improve or designparameters change more or less area may be needed for the supportingcircuits 370 of the circuit column 356.

Referring specifically to FIGS. 3 g and 3 h, the supporting circuitry370, which may include an amplifier, a filter, a clock or othercircuitry needed to support an image sensor, may all be disposed on oneor more supporting substrates, such as a second substrate 311. However,it will be appreciated that such circuits may be dispersed on one ormore substrates, such as the second substrate 311, or a third substrate.Additionally, an analog to digital converter may be remotely located onone of the supporting substrates. It will be appreciated that the orderand location of the supporting circuits 370 may be changed and may belocated on any of the supporting substrates as desired.

As can be seen in the figures, each pixel column 352 may be associatedand electrically connected to one read bus 330 on the first substrate310, while each of the circuit columns 356 may be associated andelectrically connected to one read bus 340 on the supporting substrate311 by one or more interconnects 321, which may include both ubumps 321a and vias 321 b (illustrated best in FIG. 3 h). At least oneinterconnect 321 may be used to connect a pixel column bus 330 on thefirst substrate 310 to a circuit column bus 340 on the supportingsubstrate 311 as illustrated. The dashed arrows in FIGS. 3 i, 3 j, 3 l,3 o, 3 q, 3 r, 3 t, 3 v, 3 x, 3 y and 3 aa illustrate that theinterconnects 321 may be located anywhere along the superimposition pathof the two read buses 330 and 340 per corresponding pixel column 352 andcircuit column 356.

Referring now to FIGS. 3 i through 3 m, there is illustrated variousviews of an embodiment of an imaging sensor 300 built on a plurality ofsubstrates. FIGS. 3 i and 3 m illustrate a plurality of pixel columns352 forming the pixel array 350 on the first substrate 310 and aplurality of circuit columns 356 (that represent the supportingcircuitry 370) on the second substrate 311. As illustrated, the circuitcolumns 356 may be one pixel in width and “N” number of pixels long tocorrespond directly with the pixel column 352 to which the circuitcolumn 356 is associated. The figures show an example of a connectionbetween each pixel column 352 to its associated circuitry 370 in acircuit column 356. The figures also show one read bus 330 per pixelcolumn 352 and one read bus 340 per circuit column 356, where theassociated circuitry 370 in a circuit column 356 is one pixel columnwide.

As noted herein above, each pixel column 352 may be electricallyassociated or connected to one pixel column bus 330, and each circuitcolumn 356 may be electrically associated or connected to one circuitcolumn bus 340. FIGS. 3 j through 3 l illustrate a perspective view, afront view and a side view, respectively, of a single pixel column 352and a single circuit column 356 separated from the plurality of pixelcolumns 352 and plurality of circuit columns 356 illustrated in FIG. 3i. FIGS. 3 j through 3 l further illustrate the electrical connectionbetween the buses 330 and 340 of the pixel column 352 and the circuitcolumn 356 using one or more interconnects 321. While the buses 330 and340 may be electrically connected using one or more interconnects 321,the figures illustrate that the interconnect 321 may be located anywherealong the superimposed path of the buses 330 and 340 without departingfrom the spirit or scope of the disclosure.

Referring now to FIG. 3 n through 3 t, there is illustrated variousviews of an embodiment of an imaging sensor 300 built on a plurality ofsubstrates, wherein a plurality of pixel columns 352 forming the pixelarray 350 are located on the first substrate 310 and a plurality ofcircuit columns 356 are located on a second substrate 311. In thisembodiment, the circuit columns 356 may be two pixels or two pixelcolumns in width. In this example, the connection between each pixelcolumn 352 to its associated circuitry 370 in a corresponding circuitcolumn 356 may be one read bus 330, 340 per pixel column 352 and circuitcolumn 356. As can be seen in the figure, the area consumed by the pixelcolumn 352 on the first substrate 310 corresponds to an area consumed bya corresponding circuit column 356. Such correspondence allows fordirect overlay of the substrates, for example 310 and 311, such thatsupport circuits 370 in a circuit column 356 are directly stacked withthe pixel column 352 they support.

It should also be noted that in such a configuration, the aspect ratioof the pixel column 352 will be substantially equal to the aspect ratioof the circuit column 356, however such aspect ratio equality is notrequired as discussed further below. As can be seen in FIG. 3 m thepixel column is one pixel column wide and six pixels long, so the aspectratio is 1/6. The circuit column also has the same aspect ratio of 1/6.In contrast, FIG. 3 n illustrates a design wherein the circuit columnaspect ratio is twice as wide as the pixel column aspect ratio, but isonly half as long, thereby providing a possibly more usable footprint inwhich to place supporting circuits. In both FIGS. 3 m and 3 n, the areaof the footprint of both the pixel column 352 and the circuit column 356is substantially equal to each other even though the aspect ratios aredifferent.

FIG. 3 n also illustrates how differing aspect ratios between thesubstrates can allow for flexibility in bus contact points. In theembodiment, the column circuit bus 340 has been designed with a general“u” shape that so as to occupy the area of the circuit column 356 moreevenly, thereby providing options for connecting the interconnect 321throughout the entire circuit column 356. Note that the pixel column bus330 is not generally u-shaped, but the circuit column bus 340 may begenerally u-shaped, so that the same column circuit 356 may be used withthe two different pixel column configurations of FIGS. 3 o and 3 r. Thefirst leg of the u-shaped circuit column bus 340 may be superimposed tothe read bus 330 of the first pixel column 352 (as illustrated in FIG. 3o) and the second leg of the u-shaped circuit column bus 340 may besuperimposed to the read bus 330 of the next, adjacent pixel column 352(as illustrated in FIG. 3 r). FIG. 3 o and FIG. 3 r illustrate pixelcolumns 352 taken from the pixel array 350 of FIG. 3 n. FIG. 3 o andFIG. 3 r illustrate three options for interconnect 321 positioningwithin the circuit column 356 footprint. In should be noted, asillustrated in FIG. 3 q, that because the aspect ratio of the circuitcolumn 356 is illustrated as being twice as wide, but one half thelength of the corresponding pixel column 352, the interconnect 321location options are only available for a portion of the pixel column352 length. FIG. 3 p illustrates that for a complex bus shape there maybe two interconnect location path options along a bus 340 in a circuitcolumn 356 having twice the width of the pixel column 352 it supports.FIG. 3 p illustrates a front view of the superimposition of the firstleg of the u-shaped circuit column bus 340 to the read bus 330 of thefirst pixel column 352 and uses the outer most portion of the bus 340for locating the interconnect 321 as opposed to the innermost portion ofthe bus 340 as illustrated in FIGS. 3 r and 3 s for locating theinterconnect 321 to the next, adjacent pixel column 352. FIG. 3 rillustrates the next pixel column 352 located to the left of andrelative to the first pixel column illustrated in FIGS. 3 n (right mostpixel column) and 3 o. The bus 330 of the second pixel column 352illustrated in FIG. 3 r may be electrically connected to the second legof the bus 340 as illustrated. It should be noted that because thefootprint of the circuit column 356 has an aspect ratio of 2/3, thesuperimposition of the pixel column bus 330 to the circuit column bus340 requires the second leg of the circuit column bus 340 to begenerally u-shaped to thereby allow a natural match or superimpositionof the buses 330 and 340 with respect to the next pixel column 352illustrated in FIGS. 3 r and 3 s.

FIG. 3 u illustrates a perspective view of an embodiment of an imagingsensor 300 built on a plurality of substrates wherein a plurality ofpixel columns 352 forming the pixel array 350 are located on the firstsubstrate 310 and a plurality of circuit columns 356 are located on asecond substrate 311, wherein the circuit columns 356 are four pixels inwidth, but are also one fourth the length. The figure also illustrates aplurality of electrical connections and communication paths between theplurality of pixel columns 352 and associated or corresponding columns356 of circuitry.

FIG. 3 v illustrates a perspective view of a single column of pixels 352and a single column of circuitry 356 taken from the right most column ofFIG. 3 u showing an electrical connection therebetween and anillustrative bus configuration to accommodate the architecture. As canbe seen in the figure, an embodiment may comprise a pixel column 352(and associated bus 330) that has a minimal portion of overlay with acorresponding circuit column 356 (and associated bus 340). In otherwords, very little bus superimposition is required between substrates.However, as illustrated in FIG. 3 u, there may be superimposition on thesubstrate level.

FIG. 3 w illustrates a front view of the single column of pixels 352 andthe single column of circuity 356 taken from FIG. 3 v showing anelectrical connection therebetween. As can be seen in the figure, only asmall lateral portion of bus superimposition is needed to connect thepixel column 352 to the circuit column 356.

FIG. 3 x illustrates a side view of the single column of pixels 352 andthe single column of circuitry 356 taken from FIG. 3 v showing anelectrical connection therebetween. As can be seen in the figure, one ormore interconnects 321 can be used in some embodiments and the figurealso illustrates that the placement of the interconnects 321 may beanywhere along the superimposition of the buses 330 and 340.

FIG. 3 y illustrates a perspective view of a single column of pixels 352and a single column of circuitry 356 taken from the column to the leftof, and adjacent to, the right most column 356 of FIG. 3 u showing anelectrical connection therebetween. FIG. 3 z illustrates a front view ofthe single column of pixels 352 and the single column of circuitry 356taken from FIG. 3 y showing an electrical connection therebetween. FIG.3 v and FIG. 3 y illustrate pixel columns 352 taken from the pixel array350 of FIG. 3 u. FIG. 3 v and FIG. 3 y illustrate two options forinterconnect 321 positioning within the circuit column 356 footprint. Itshould be noted, as illustrated in FIG. 3 aa, that because the aspectratio of the circuit column is wider, but shorter than that of thecorresponding pixel column 352, the interconnect location options areonly available for a portion of the pixel column 352 length. FIG. 3 zillustrates that for a complex bus shape there may be four interconnectlocation path options along a bus 340 in a circuit column 356 havingfour times the width and one fourth the length of the pixel column 352it supports. Thus, it can be seen that while the aspect ratio of thecircuit column 356 is different than the aspect ratio of the pixelcolumn 352, the areas of the respective footprints are substantially thesame or equal. As manufacturing techniques improve or design parameterschange more or less area may be needed for the supporting circuits ofthe circuit column 356.

FIGS. 3 v and 3 w illustrate the superimposition of the first pixelcolumn read bus 330 with the first leg of the circuit column read bus340. FIG. 3 y illustrates the next, adjacent pixel column relative tothe pixel column illustrated in FIG. 3 v. It should be noted thatbecause the footprint of the circuit column 356 has an aspect ratio of4/2, the superimposition of the pixel column bus 330 to the circuitcolumn bus 340 requires the second leg of the circuit column bus 340 tobe shaped accordingly to thereby allow a natural match orsuperimposition of the buses 330 and 340 with respect to the next pixelcolumn 352 illustrated in FIGS. 3 y and 3 z FIG. 3 aa illustrates a sideview of the single column of pixels and the single column of circuitrytaken from FIG. 3 y showing an electrical connection therebetween.

It will be appreciated that each of the pixel columns may be shared orunshared with respect to a read bus, depending upon the conditionspresent that may affect pixel design and architecture. Illustrated inFIGS. 12 and 13 are two examples of pixel architecture. FIG. 12illustrates a pixel architecture where each pixel column does not sharea read bus with another pixel column. This example, when there is onlyone read bus per pixel column, illustrates an unshared pixelarchitecture. Conversely, illustrated in FIG. 13 is a horizontal 2-waypixel share. In FIG. 13, there is only one read bus per two pixelcolumns. Note that the number of read buses per pixel column may be animportant consideration in embodiments where the pixel array 350 isoptimized on a first substrate and separated from the majority of thesupporting circuitry located on a second or supporting substrate in athree dimensional stacking embodiment as discussed herein.

It should be noted that it is within the scope of the disclosure toallow for a plurality of pixel columns to correspond to a set of supportcircuits in a circuit column. For example, because the processing powerof some support circuits may be greater than what is required by thedata generated by a pixel column, a plurality of pixel columns maycorrespond to a circuit column. The converse is also contemplatedherein, wherein certain embodiments a plurality of circuit columns maycorrespond to a single pixel column in a pixel array.

In an embodiment of the specific process and implementation describedabove, the connection may be done though an interconnect, such as aubump, located between the two substrates/chips. Both metal layers ofthe two substrates/chips may face each other, therefore back sideillumination may be needed on the CMOS image sensor chip comprising thepixel array (front-side of the first chip may be bonded to front-side ofthe second chip). In an embodiment, there may be only one interconnectused per column 352, 356 between the first substrate/chip and the secondsubstrate/chip. In an embodiment, two or more interconnects may be usedper column 352, 356 and may be used for redundancy purposes (processyield). Compared to conventional technology (monolithic CMOS imagesensor as shown in FIGS. 3 a through 3 f), the read bus may be broken atthe edge of the pixel array and may be replicated in the secondsubstrate/chip. A bump may then connect the two buses anywhere withinthe column. It will be appreciated that more interconnects, such asubumps, may be needed for power distribution between the two or moresubstrates/chips or for other signals (e.g., vertical decoder).

Referring now to FIG. 4, an embodiment of an image sensor with its pixelarray and supporting circuitry built on a plurality of substrates isillustrated using backside illumination. As can be seen in the figure, apixel array 450 may be disposed on a first substrate 452. The firstsubstrate 452 may be made of silicon or of another material in order tocontrol light transmission characteristics. Solder balls, bumps or vias421 may be used to electrically connect one substrate to another. Anembodiment of a stacked image sensor may comprise a pixel array 450 on afirst substrate 452. The pixel array 450 may cover at least fortypercent of a first surface 451 of the first substrate 452. In a backsideilluminated configuration, a pixel array 950 may be disposed on thebackside of said first substrate 952 as illustrated best in FIG. 9.Further, in a back side illumination configuration the substrate 452 maybe thinned for controlling light transmission therethough. In anembodiment utilizing backside illumination, the first substrate may bemade of primarily silicon material, or the first substrate may be madeof primarily of “High-Z” semiconductor material (Cadmium Telluridee.g.), or the first substrate may be made primarily of III-Vsemiconductor materials (Gallium Arsenide e.g.).

In an embodiment, a pixel array 450 may cover a majority of the firstsurface 451 of a first substrate 452. In such an embodiment the pixelarray 450 may be situated or located on any portion of said firstsurface 451. The remaining space on the first surface 451 may be usedfor secondary circuit placement if desired. Situations may arise where asecondary circuit may be sized such that central placement of the pixelarray is not practical.

Referring now to FIG. 5, an embodiment will be discussed wherein atleast some of the supporting circuitry and components are remotelylocated from other supporting circuitry and components in order to workfor a predetermined purpose. For some applications, it may be desirousfor certain secondary processors to be more remotely located from thepixel array. For example, in a medical scope such as an endoscope theremay not be enough room around the pixel array to contain all of theneeded support circuitry. In such cases, the pixel array containingsubstrate 510 may be remotely located a distance away from othersupporting substrates within the image sensor 500.

In an embodiment, the pixel array containing substrate 510 may beadjacent to or near a support substrate 520 that is located remotelywith respect to the pixel array containing substrate. The supportsubstrate 520 may comprise an amplifier circuit thereon, while othersupporting circuits may be more remotely located on another substrate530 a distance that is farther away from the pixel array substrate 510than the distance support substrate 520 is located away from the pixelarray substrate 510. In an embodiment the more remotely locatedsubstrate 530 may be connected to the other substrates in the imagesensor 500 by wire vias 522 or may communicate wirelessly with the othersubstrates and circuits. Adjacent substrates may be connected to eachother by way of bumps or solder balls 521. As pixel arrays and othercircuits become more efficient over time, it is within the scope of thisdisclosure to provide an image sensor wherein the pixel array containingsubstrate is more remote from all other support circuits. Such a circuitis pictured in FIG. 10, wherein a pixel array containing substrate 1010is more remotely located by way of vias 1022 from support substrates1020, 1030, 1040 each comprising support circuits such as signalprocessing circuits and power circuits.

In an embodiment, the pixel array of an image sensor may dominate alarge percentage of the available surface area of a first substrate 570.As can be seen in FIG. 6, various sized pixel arrays 572, 574, 576(shown in dashed lines) are contemplated by the disclosure and fallwithin the scope of the design disclosed. Pixel array 576 schematicallyrepresents a configuration wherein the pixel array 576 covers a largepercentage of a first substrate 570, but yet may not cover a majority ofthe substrate 570. Pixel array 576 may cover such a large percentage ofthe available area, even though not a majority of the area, such that atleast some of the supporting circuitry may not be located on the firstsubstrate 570.

Pixel array 574 schematically illustrates a separate configuration frompixel array 576 and 572, wherein the pixel array 574 coversapproximately half of a first substrate 570. Pixel array 572schematically illustrates a separate configuration from pixel array 576and 574, wherein the pixel array covers a clear majority of the firstsubstrate 570. It should be apparent from the discussion above that theoptimization process may allow for finding a pixel array size thatprovides the best possible image and image quality while working withinconstraints dictated by an application, function or purpose.Accordingly, even in an application having an imaging sensor with afixed first substrate size, the percentage of the surface area occupiedby the pixel array located on the first substrate may differ and covermany different percentages of the total surface area available on thefirst substrate.

Thus, it will be appreciated that the surface area that the pixel arraymay occupy may fall within a range that is about 25% to about 99% of thetotal surface area of one of the surfaces of the first substrate, or maybe within a range of about 40% to about 99% of the total surface area ofone of the surfaces of the first substrate, or may be within a range ofabout 50% to about 99% of the total surface area of one of the surfacesof the first substrate, or may be within a range of about 60% to about99% of the total surface area of one of the surfaces of the firstsubstrate, or may be within a range of about 70% to about 99% of thetotal surface area of one of the surfaces of the first substrate, or maybe within a range of about 80% to about 99% of the total surface area ofone of the surfaces of the first substrate, or may be within a range ofabout 90% to about 99% of the total surface area of one of the surfacesof the first substrate. It will be appreciated that all percentages thatfall within the stated ranges are intended to fall within the scope ofthe disclosure. It will further be appreciated that all sub-rangesfalling within the range of about 25% to about 99% of the total surfacearea of one of the surfaces of the first substrate are intended to fallwithin the scope of the disclosure.

Because of the nature of a backside illuminated pixel array, thesubstrate surfaces discussed above may be extraneous to an image sensorcomprising a backside illuminated pixel array. Thus, in backsideilluminated applications, the substrate surface may be eliminated orformed integrally with the pixel array.

Pixel array coverage or surface area may be within a range of about 40%to about 70% of the total surface area of the substrate upon which thepixel array resides, and in such cases it may be possible to place somesupport circuitry thereon without diminishing from the design of theimage sensor. In an embodiment, a light emitting circuit may occupy somespace on the first substrate to provide light during use. For manyapplications, where dimensions are extremely tight and are the mosttightly constrained, an optimized imaging sensor may cover 90% or more,up to substantially all of a surface area of a first substrate. Itshould be noted that it is within the scope of this disclosure tocontemplate a pixel array having an integrated substrate therein ratherthan being added to a substrate.

Illustrated in FIG. 7 is an embodiment of an imaging sensor having aplurality of pixel arrays. As can be seen in the figure, an image sensor700 may comprise a first image sensor 710 and a second image sensor 711,which are in electrical communication with a substrate 715 or aplurality of substrates that may be stacked vertically or otherwise withrespect to an object to be imaged. In an embodiment, supporting circuitsmay be remotely located on subsequent or supporting substrates asdiscussed above. Such a configuration may be desirable for threedimensional image capture, wherein the two pixel arrays may be off setduring use. In another embodiment, a first pixel array and a secondpixel array may be dedicated to receiving a predetermined range of wavelengths of electromagnetic radiation, wherein the first pixel array isdedicated to a different range of wave length electromagnetic radiationthan the second pixel array.

Illustrated in FIGS. 14 and 15 is an embodiment for retrieving data froma pixel array 1510 that has been optimized on a first substrate 1552(see FIG. 15) with supporting circuitry 1520 for an image sensor 1500located on one or more second, or supporting, substrates 1554 (see FIG.14), which may be configured in a stacked configuration (FIGS. 14 and 15combined). As can be seen in the figures, a pixel array 1510 may belocated on the first substrate 1552 and may be electrically connected tosupport circuits 1520 that may reside on one or more subsequent orsupporting substrates 1554 (FIG. 14) with one or more interconnects1521. In the embodiment illustrated in FIGS. 14 and 15, the pixel array1510 may be comprised of a plurality of pixel columns 1550 a-f. Each ofthe pixel columns 1550 a-f may be comprised of a plurality of individualpixels and the pixel columns 1550 a-f may be read through correspondingpixel column buses 1551. It will be appreciated that there may be oneread bus 1551 per pixel column 1550 within the entire pixel array 1510.It should be noted that the plurality of individual pixels 1526 may beformed in columns (y axis) and rows (x-axis) that denote or define theposition of the individual pixel 1526 within the pixel array 1510.

As illustrated in the figures, each of the plurality of pixel columnread buses 1551 may provide an electrical connection for a predeterminedor defined pixel column 1550, such as 1550 a, 1550 b, 1550 c, 1550 d,1550 e, and 1550 f in FIG. 15. In such an embodiment, data collectedfrom the pixels 1526 within the predetermined or defined pixel column,for example 1550 a, may be transmitted to support circuits 1520 locatedon one or more second, subsequent or supporting substrates 1554 via thecircuit column read bus 1516 (see FIG. 14) and/or through one or moreinterconnects 1521. Circuits 1520 may be located on either side of thesupport substrate 1554 and electrical contact may be facilitated throughvias disposed in the substrate material and running through thesubstrate. The subsequent substrate 1554 may comprise a plurality ofcircuit columns, each circuit column comprising a plurality of circuits1520 and a bus 1516 for electrically connecting the various circuits1520 within the circuit column within the image sensor 1500. It shouldbe noted that the spacing between interconnects 1521, which may be usedto connect the pixel column buses 1551 to the circuit column buses 1516,has been increased in the figure by staggering the interconnects 1521relative to the pixel columns 1550 a-f. The dashed lines illustrated onsubstrate 1554 illustrate an area on the substrate that corresponds tothe area consumed by the pixel column 1550 on the first substrate 1552.

In an embodiment, it may be desirable to design an image sensor 1500where support circuits 1520 for any given pixel column 1550 are placedwithin a corresponding area located on a second substrate. It should benoted that in an embodiment, one or more dedicated support circuits 1520may be used per pixel column or area 1550, such that each pixel area1550 a-1550 f has at least one support circuit 1520 dedicated toprocessing only the data produced by the pixels 1526 within thatpredetermined or defined pixel column represented by pixel columns 1550a-1550 f to which the support circuit is dedicated. For example, eachpixel column area 1550 a-1550 f may have a dedicated analog-to-digitalconversion circuit dedicated to converting the analog data read from theassociated pixels 1526 from within the associated pixel column 1550.This close and direct association of dedicated circuits can be used, tosimplify the digital signal processing within the image sensor 1500thereby greatly simplifying the timing and serializing processes withinthe image sensor 1500. Such a feature can also be used to control heatproduction and energy consumption within the image sensor 1500.

Referring primarily to FIG. 16, a multi-substrate image sensor 1600having a read bus configuration therein is illustrated. As can be seenin the figure, a substrate 1652 may contain a pixel array 1610 and maybe electrically connected to support substrates 1654 and 1656 through aplurality of pixel column read buses. Image sensor architecture can begreatly simplified by locating the support circuits on one or moresubsequent substrates 1654 and 1656. The subsequent substrates 1654 and1656 may be in close proximity to, but behind, the first substrate 1652.Support circuits 1622 and 1663 may be placed on the subsequentsubstrates 1654 and 1656 in order to allow for the stacking of thesubstrates in a vertical configuration as illustrated. Through substratevias may be used to enable front to back communication through any ofthe substrates. The second substrate 1654 in the stack may comprisesecondary circuits that are dedicated to pixel columns 1650 located onthe first substrate 1652 and electrically connected therewith. The thirdsubstrate 1654 may comprise additional data processing circuits 1663that may be dedicated to support circuits 1622 on the second substrate,and may be purposed to process data from a plurality of support circuitsfrom the second substrate. It should be noted that circuits 1663 on thethird substrate 1656 may be dedicated to a specific pixel column 1650 onthe first substrate 1652, or may be dedicated to process data from aplurality of pixel columns 1650. In other words, circuits 1663 locatedon the third substrate 1656 may directly correspond to specific circuits1622 on the second substrate 1654 or specific pixel columns 1650 on thefirst substrate 1652. It should be noted that each substrate maycomprise at least one bus that electronically connects circuitry on allof the substrates. Accordingly, the buses 1623 a-1623 c of each of thesubstrates may be superimposed such that interconnects 1621 disposedbetween the substrates cause electrical connection between the buses1623 a-1623 c.

As can be seen in the figure, a column of pixels 1650 located on thefirst substrate 1652 may be electrically connected to support circuitslocated on one or more supporting substrates 1654, 1656 through directpixel column reading by placement of one or more strategically locatedinterconnects 1621 within the pixel column 1650 or the bus system 1623a-1623 c. Each of the plurality of substrates 1652, 1654, and 1656 thatmake up the image sensor 1600 may comprise its own bus or bus system1623 a, 1623 b, and 1623 c, respectively. Accordingly, it may beadvantageous to connect each of the buses 1623 together to form a busskeletal system 1630 from one layer of substrate to the next. Forexample, the first substrate 1652 comprising the optimized pixel array1610 as disclosed herein may be connected to support circuits 1622,which reside on the second, subsequent substrate 1654 through the use ofinterconnects 1621 located within the predetermined or defined pixelcolumn 1650 and interconnect 1621, which may be located anywhere alongthe path of the superimposed bus system 1623.

As illustrated, the first interconnect 1621 a may be used to connect thefirst pixel column 1650 and pixel column bus 1623 a directly to thesecond bus or bus system 1623 b and support circuits 1622 located on thesecond substrate 1654, while the second interconnect 1621 b may be usedto connect the second bus or bus system 1623 b residing on the secondsubstrate 1654 to a third bus 1623 c residing on the third substrate1656. Additionally as illustrated in FIG. 16, the bus skeletal system1630 may be extended beyond the first and second substrates 1652 and1654 and may continue and electrically connect the second substrate 1654to the third substrate 1656 and so on until all substrates have beenelectrically connected through the bus skeletal system 1630. The bus1623 b located on the second substrate 1654 may be connected to thethird bus 1623 c that may be located on the third substrate 1656 and soon until all substrates have been electrically connected together. Thus,the predetermined or defined pixel column 1650 may be in electricalcommunication with a support circuit 1622 that may reside remotely onthe second substrate 1654 or a support circuit 1663 that may resideremotely on the third substrate 1656 through the respective buses 1623a-1623 c located on the plurality of substrates.

It should be noted that because a single interconnect 1621 may be usedto read a column 1650 containing a plurality of pixels, the interconnectspacing or pitch may be considerably larger than the pixel pitch of thepixel array 1610.

During use, data created by individual pixels on the pixel array must beprocessed by supporting circuitry, as such each pixel 1726 must beelectronically connected to the supporting circuits 1770 on the secondsubstrate 1754. Ideally each pixel could be read simultaneously therebycreating a global shutter. Referring now to FIG. 17 a, it will beappreciated that the ability to read data from an imaging device as aglobal shutter requires that there be one interconnect 1724 per pixel1726, which is very difficult to achieve in practice because of thebumping pitch in manufacturing tolerances. FIG. 17 b illustrates asituation where the pixels 1726 have been formed in columns 1728, wherethe bump pitch requirements remain the same in the horizontal direction.A bump pitch of about 5 μm is required for pixels near that size,whereas utilizing three dimensional stacking technology and interconnectstaggering disclosed herein may allow for a bump pitch of about 20 μm toabout 200 μm in actual production. Therefore, a very high frame raterolling type shutter that also uses the stacking technology in threedimensions may be considered a substantial improvement. In the case of arolling shutter, only one interconnect/bump 1724 per pixel column 1728is required instead of one interconnect/bump 1724 per pixel 1726.

FIG. 17 a illustrates a bumping configuration or scheme using one bump1724 per pixel 1726, which approximates a global shutter operation. Inthis configuration, the bump pitch equals or substantially equals thepixel pitch in both the X and Y axes or directions.

FIG. 17 b illustrates a bumping configuration or scheme using oneinterconnect/bump 1724 per pixel column 1728, This configuration may beused in a rolling shutter operation. This bump pitch configuration orscheme is more relaxed as compared to the bump pitch of FIG. 17 a in thevertical direction only. However, it should be noted that in thisconfiguration the bump pitch is still required to be at least the samein one direction or dimension as the pixel pitch. FIG. 17 b illustratesa plurality of columns 1728, where each column 1728 is comprised of aplurality of pixels 1726. Each column of pixels may run in the Ydirection (y-axis) for a distance and may be one pixel in width asillustrated. Each column of pixels may be read through a singleconnection point at one end of each column 1728. Although such aconfiguration simplifies chip architecture, tight tolerances must stillbe maintained because the distance between pixels laterally(horizontally) continues to limit bump (interconnect) pitch because theinterconnect must not make contact with a neighboring interconnect andmust be sized accordingly.

FIG. 17 c, illustrates a bumping configuration that is even furtherrelaxed than that shown in FIG. 17 a or 17 b. In this figure, the bumppitch is relaxed and half of the interconnects/bumps 1724 can beprocessed at each side of the pixel array 1710 by adding or introducinga second set of interconnects 1724 at alternating and opposing ends ofthe columns 1728. As can be seen in FIG. 17 c, the second set ofinterconnects may be used in combination with the first set ofinterconnects and may be employed to allow half of the data to beprocessed or read at each side of the pixel array 1710. Such aconfiguration may allow for nearly double the size of bump pitch(interconnect) as compared to the pixel pitch in at least one dimension,which would greatly decrease the cost of producing image sensors 1700.In an embodiment, more than one interconnect or bump 1724 per pixelcolumn 1728 may be utilized, such that data may be read from either endof the pixel column 1728.

FIGS. 18 a-18 f illustrate embodiments and configurations of a pixelarray 1810 having staggered interconnect or bump 1824 positioning on asubstrate/chip. As noted above, because there is one read bus per pixelcolumn 1828 and one read bus per circuit column, and because the readbuses run from the top of the column to the bottom of the column, theinterconnect/bump 1824 may be placed anywhere along the superimposedpath of the buses within the column. In order to relax the bumpingpitch, the bump distance may be increased from column to column byshifting the next column bump 1824 either up or down (in the Ydirection) in the next column.

By way of example, it will be appreciated that pixel pitch may be about5 μm and pixel column may be any length, for example between about 2 mmand about 15 mm long. It should be noted that bump pitch is a functionof pixel pitch, such that the pixel pitch will be determinative of anideal bump pitch. For example, assuming there is a desired bump pitch ofapproximately 100 μm, placing a first interconnect or bump 1824 may thenbe accomplished, by starting at the top of the first column and shiftingdown the next column interconnect or bump by 100 μm. All other bumps aresimilarly positioned until the interconnect or bump in the 20th columnof the line will be located at the bottom of the pixel column. At thatpoint, the interconnect or bump in the 21st column may again be placedat the top of the pixel column. This same pattern may then be repeateduntil the end of the pixel array. Horizontally, the interconnects orbumps may be separated by 20 columns×5 μm=100 μm. In this example, allbumps will then be separated by more than 100 μm, even though the pixelpitch is about 5 μm. Redundancy can then be introduced in the pixelcolumn for yield purposes. For example, bumps in all columns can bedoubled (i.e., the two read buses are attached by 2 interconnects orbumps). This technique would significantly increase stacking yield andlower the cost of the overall process.

As can be seen in FIG. 18 a, a first column 1828 of pixels 1826 may beelectrically accessed via a first interconnect 1824 a. In theembodiment, a second pixel column 1830 may be electrically accessedthrough a second interconnect 1824 b, which has been positioned duringmanufacture in a staggered configuration relative to said firstinterconnect 1824 a. As illustrated, the location or position of thesecond interconnect 1824 b may be at least two pixel widths away fromthe position of the first interconnect 1824 b (and from any otherinterconnect 1824) in both the X and Y dimensions or directions. A thirdinterconnect 1824 c may then be positioned in like manner in a thirdpixel column and so on for N-number of interconnects 1824 across thepixel array 1810. Such a configuration provides for an interconnectpitch that is at least three times that of the pixel pitch. It will beappreciated that the gain in interconnect pitch may be much greater thanthree times that of the pixel pitch under standard conditions. However,it will be appreciated that the gain in interconnect pitch may be atleast three times the pixel pitch as noted above.

Likewise, greater interconnect gains may be made with area based spacingrather than column-by-column based connectivity (see figures anddiscussion relating to FIGS. 3 m, 3 n and 3 u, which illustrate a pixelcolumn aspect ratio of 6/1 and circuit column aspect ratio of 6/1 (forFIG. 3 m) and 3/2 (for FIG. 3 n), and a pixel column aspect ratio of 8/1and circuit column aspect ratio of 2/4 (for FIG. 3 u)). This can beaccomplished with the addition of more bus structures or use of directreading to a subsequent substrate. In either configuration, theinterconnect pitch may be described thusly:

Interconnect_Pitch=√{square root over((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}{square root over((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}

where N is the number of pixels between two adjacent interconnects inthe X-direction and M is the number of pixels between two adjacentinterconnects in the Y-direction. It will be appreciated that each ofthe plurality of interconnects may be a bump where the bump to bumpdistance may be greater than two pixels in width, or greater than fourpixels in width, or greater than eight pixels in width.

In many applications, the N×Pixel Pitch in the X direction will be equalto M×Pixel Pitch in the Y direction. As illustrated in FIGS. 18 b-18 f,larger pixel arrays 1810 may be accommodated or designed byextrapolating the above described process through additional iterations.FIG. 18 b illustrates a superimposed silicon substrate stack. In thefigure, a first substrate 1852 consisting of a pixel array is shownoverlaid on top of a support substrate 1854 that comprises supportcircuits. The area available for locating support circuits for a firstpixel column 1881 is outlined in dashed lines and labeled for the sakeof simplicity and discussion. It will be appreciated that the actualarea of the circuit column is not represented by the dashed lines, butmay be greater than, less than or the same as the area of the pixelcolumn. As discussed, above, the support circuit area directlycorrelates to the area of a pixel column to which they correspond. Eachpixel column may be one pixel wide and sixty-four pixels long and mayhave one read bus that runs from the top to the bottom of the pixelcolumn. In FIG. 18 b the area available for support circuit placementmay be equal to one pixel unit wide by sixty-four pixel units long,which is shown as the heavier vertical lines in the figure. Therefore,the interconnect 1824 between the substrates in FIG. 18 b must fallsomewhere within the sixty-four pixel unit area in order to read thatcolumn, since the pixel column read bus and the column circuit read busare superimposed along the path of the sixty-four pixels, such that theinterconnect 1824 may be placed anywhere along those sixty-four pixelsto connect the read buses.

Moreover, because the interconnect can happen only where the pixelcolumn read, bus and the support circuit read bus superimpose, theinterconnect range in order to read the corresponding pixel column is 1pixel wide and 64 pixels long (for this example), which is the interceptbetween the pixel column and the support circuit to be connected.

It should be noted that the exemplary aspect ratio of the supportcircuit area in FIG. 18 b is illustrated as 1/64. There are many optionsto locate or place the interconnect 1824 within that area and theultimate location may then be chosen by the designer so as to allow thedesired spacing from interconnect to interconnect. For example, asillustrated best in FIGS. 18 b-18 f, it will be appreciated that in anembodiment in which the interconnects or bumps 1824 are in a staggeredconfiguration, there may be one interconnect or bump 1824 per group ofpixels 1826.

Additionally, it should be noted that various read bus architectures maybe utilized depending on the desired application. As discussed above,larger dedicated support circuits may be employed to process the dataread through each interconnect 1824. The staggering of the position ofeach interconnect/bump 1824 may also provide even greater space forsupport circuits relative to each area or group of pixels within thepixel array 1810.

It should also be noted that many optimum staggering configurations havebeen found for the same base sensor with different support circuitaspect ratios as illustrated in FIGS. 18 b to 18 f. An optimumconfiguration can be found by varying the position of the interconnectwithin the range of the intercept between the pixel column and thesupport circuit and the pattern of the allocation of the support circuitto each pixel column. It should also be noted that all interconnectsillustrated in FIGS. 18 b to 18 f are more than 7 pixels in distanceaway from each other.

In FIG. 18 c the area available for support circuit placement may beequal to two pixel units wide by thirty-two pixel units long, which isshown as the heavier vertical lines in the figure. Therefore, theinterconnect between the substrates 1852 and 1854 must fall somewhere inthe sixty-four pixel unit area in order to read that column. It shouldbe noted that the aspect ratio of the support circuit area in thisexample is 2/32, Each pixel column is or may be one pixel wide andsixty-four pixels long and may have one read bus that runs from the topto the bottom of the pixel column. The choice of where to place theinterconnect has many options within that area and could be chosen so asto allow the desired spacing from interconnect to interconnect.Moreover, because the interconnect can be located only where the pixelcolumn read bus and the support circuit read bus superimpose, in orderto read the corresponding pixel column the interconnect range may be onepixel wide and thirty-two pixels long (for this example), which is theintercept between the pixel column and the support circuit to beconnected.

In FIG. 18 d the area available for support circuit placement may beequal to four pixel units wide by sixteen pixel units long, which isshown as the heavier vertical lines in the figure. Therefore, theinterconnect between the substrates must fall somewhere in thesixty-four pixel unit area in order to read the corresponding pixelcolumn. It should be noted that the aspect ratio of the support circuitarea in this example is 4/16. Each pixel column is or may be one pixelwide and sixty-four pixels long and may have one read bus that runs fromthe top to the bottom of the pixel column. The choice of where to placethe interconnect has many options within that area and could be chosenso as to allow the desired spacing from interconnect to interconnect.

Moreover, because the interconnect can be located only where the pixelcolumn read bus and the support circuit read bus superimpose, in orderto read the corresponding pixel column the interconnect range may be onepixel wide and sixteen pixels long (for this example), which is theintercept between the pixel column and the support circuit to beconnected.

In FIG. 18 e the area available for support circuit placement may beequal to eight pixel units wide by eight pixel units long, which isshown as the heavier vertical lines in the figure. Therefore, theinterconnect 1824 between the substrates 1852 and 1854 must fallsomewhere in the sixty-four pixel unit area in order to read thecorresponding pixel column. It should be noted that the aspect ratio ofthe support circuit area in this example is 8/8. Each pixel column is ormay be one pixel wide and sixty-four pixels long and may have one readbus that runs from the top to the bottom of the pixel column. The choiceof where to place the interconnect has many options within that area andcould be chosen so as to allow the desired spacing from interconnect tointerconnect.

Moreover, because the interconnect can be located only where the pixelcolumn read bus and the support circuit read bus superimpose, in orderto read the corresponding pixel column the interconnect range may be onepixel wide and eight pixels long (for this example), which is theintercept between the pixel column and the support circuit to beconnected.

In FIG. 18 f the area available for support circuit placement may beequal to sixteen pixel units wide by four pixel units long, which isshown as the heavier vertical lines in the figure. Therefore, theinterconnect between the substrates must fall somewhere in thesixty-four pixel unit area in order to read the corresponding pixelcolumn. It should be noted that the aspect ratio of the support circuitarea in this example is 16/4, this example shows the flexibility thatthese methods and apparatuses disclosed, herein can provide. Each pixelcolumn is or may be one pixel wide and sixty-four pixels long and mayhave one read bus that runs from the top to the bottom of the pixelcolumn. The choice of where to place the interconnect has many optionswithin that area and could be chosen so as to allow the desired spacingfrom interconnect to interconnect.

Moreover, because the interconnect can be located only where the pixelcolumn read bus and the support circuit read bus superimpose, in orderto read the corresponding pixel column the interconnect range may be onepixel wide and four pixels long (for this example), which is theintercept between the pixel column and. the support circuit to beconnected.

It should also be noted that the pattern of the association of thesupport circuit to the pixel column may be different than that of FIGS.18 b through 18 f and such association may ultimately provide theoptimal distance of the interconnects away from each other. For example,the interconnects may be optimally placed at least two pixel widthsapart, four pixel widths apart, eight pixel widths apart, or more fromeach other. A designer may optimally determine the distance that theinterconnects may be placed apart from one another based on two degreesof freedom: (1) the number of pixels per column, and (2) the circuitaspect ratio and location. In the examples shown in FIGS. 18 b-18 f, theinterconnects 1824 may be located about eight pixels away from eachother. However, it will be understood that other designs may beimplemented without departing from the spirit or scope of thedisclosure.

For example, as illustrated in FIG. 18 b, each of the interconnects 1824may be located eight pixels in length and one pixel in width away fromeach other. Because the circuit columns each have an aspect ratio of onepixel in width and sixty-four pixels in length, the interconnects 1824may then be located eight pixels away from each other in adjacentcolumns as illustrated in FIG. 18 b, until the bottom of the circuit1800 is reached, in which case the interconnects 1824 are then moved tothe top of the next column and continue for the entire width of thepixel array 1810. Conversely, in FIG. 18 f, the interconnects 1824 arestill located eight pixels in length and one pixel in width away fromeach other. However, in this example, the circuit column aspect ratio isnow four pixels in length and sixteen pixels in width. Thus, for theinterconnects 1824 to be at least eight pixels away from each other, onecircuit column 1856 b must be skipped since the aspect ratio is onlyfour pixels in length, such that the interconnects 1824 maintain optimalspacing. Thus, for example, placing an interconnect 1824 in the upperleft corner of the pixel array 1810 in FIG. 18 f (on the first pixel ofthe first column 1828) and then moving to the next pixel column 1830 andcounting down eight pixels in length, the next interconnect 1824 maythen be placed in the third circuit column 1856 c, skipping the secondcircuit column 1856 b altogether. This pattern may be used throughoutthe pixel array. The second, skipped circuit column 1856 b is thenconnected to the pixel array by an interconnect 1824 a that is placed inthe ninth pixel column and the pattern is repeated for all skippedcircuit columns. Thus, as illustrated, optimal interconnect spacing maybe achieved and various circuit designs may be accommodated withoutdeparting from the scope of the disclosure.

Referring back to FIG. 7, in addition to the first image sensor 710 andthe second image sensor 711, which are in electrical communication witha substrate 715 or a plurality of substrates, there is illustrated anembodiment of an imaging sensor having a plurality of pixel arrays thatmay be configured with staggered interconnects as discussed hereinabove. Such a configuration may be desirable for three dimensional imagecapture, wherein the two pixel arrays may be off set during use. Inanother embodiment, a first pixel array and a second pixel array may bededicated to receiving a predetermined range of wave lengths ofelectromagnetic radiation, wherein the first pixel array is dedicated toa different range of wavelength electromagnetic radiation than thesecond pixel array.

FIG. 19 illustrates a design and testing methodology related tooptimizing a pixel array on a first substrate. A step may be to decideon the available tolerancing differences for manufactures for an imagingsensor. A design may then be processed and bump pitch may be determinedfor a certain criteria. A simulated test sensor may then be tested andread and redesigned if desired.

FIG. 20 illustrates an embodiment having at least one dedicated supportcircuit for a given pixel area. A plurality of dedicated supportcircuits 2060 a-2060 f may be used in an imaging device 2000 and may bestacked with respect to the pixel array 2010 according to the principlesof the disclosure. The pixel array 2010 may comprise a plurality ofpixel areas 2050. Each of the plurality of pixel areas, such as 2050a-2050 f, may comprise at least one support circuit 2060 dedicated toprocessing only the data produced by the plurality of pixels 2026 withina given predetermined or defined pixel area 2050 to which the dedicatedcircuit 2060 is devoted. For example, each pixel area 2050 may have adedicated analog to digital conversion circuit dedicated to convertingthe analog data read from the associated pixels 2026 from within theassociated pixel area 2050. This close and direct association ofdedicated circuits can be used to simplify the digital signal processingwithin the image sensor thereby greatly simplifying timing andserializing processes within the image sensor. Such a feature can beused to control heat production and energy consumption within the imagesensor.

In FIG. 21 illustrates a schematically large image sensor showing thescalability of the principles and teaching of the disclosure. Each pixelcolumn is or may be one pixel wide and one-hundred and twenty-eightpixels long. Note that this has been chosen as an example forrepresenting the teaching of the disclosure, but it should be noted thatany number of pixels for the column length is possible and may be usedwithout departing from the scope of the disclosure. It should be furthernoted that the number of pixels for the column length may be an even orodd number and does not have to be a power of 2. As can be seen in thefigure, the area available for support circuit placement may be equal tofour pixel units wide by sixteen pixel units long, which is shown as theheavier vertical lines in the figure. Therefore, the interconnectbetween the substrates must fall somewhere in the sixty-four pixel unitarea. Moreover, because the interconnect can be located only where thepixel column read bus and the support circuit read bus superimpose, inorder to read the corresponding pixel column the interconnect range maybe one pixel wide and sixteen pixels long (for this example), which isthe intercept between the pixel column and the support circuit to beconnected. It should be noted that the aspect ratio of the supportcircuit area in this example is 4/16. The choice of where to place theinterconnect has many options within that area and could be chosen so asto allow the desired spacing from interconnect to interconnect. As thefigure illustrates, by repeating the methods of this disclosure even thelatest imaging sensor technology can be used with these methods. Itshould also be noted that there may be a plurality of interconnects(2516 and 2518) for any give pixel column so as to allow for moreflexibility (pixel column parallel processing e.g.) for large arrayconfigurations.

In FIG. 22 illustrates a schematically large image sensor showing thescalability of the principles and teaching of the disclosure. Each pixelcolumn is or may be one pixel wide and one-hundred and twenty-eightpixels long. Note that this has been chosen as an example forrepresenting the teaching of the disclosure, but it should be noted thatany number of pixels for the column length is possible and may be usedwithout departing from the scope of the disclosure. It should be furthernoted that the number of pixels for the column length may be an even orodd number and does not have to be a power of 2. As can be seen in thefigure, the area available for support circuit placement may be equal totwo pixel units wide by thirty-two pixel units long, which is shown asthe heavier vertical lines in the figure. Therefore, the interconnectbetween the substrates must fall somewhere in the sixty-four pixel unitarea. Moreover, because the interconnect can be located only where thepixel column read bus and the support circuit read bus superimpose, inorder to read the corresponding pixel column the interconnect range maybe one pixel wide and sixteen pixels long (for this example), which isthe intercept between the pixel column and the support circuit to beconnected. It should be noted that the aspect ratio of the supportcircuit area is 2/32. The choice of where to place the interconnect hasmany options within that area and could be chosen so as to allow thedesired spacing from interconnect to interconnect. As the figureillustrates, by repeating the methods of this disclosure even the latestimaging sensor technology can be used with these methods. It should alsobe noted that there may be a plurality of interconnects (2616 and 2618)for any give pixel column so as to allow for more flexibility (pixelcolumn parallel processing e.g.) for large array configurations. Itshould be noted that FIGS. 21 and 22 represent the same pixel array withthe only difference between the two figures is the aspect ratio of thesupport circuitry has changed (i.e., 4/16 aspect ratio in FIG. 21 and2/32 aspect ratio in FIG. 22).

It will be appreciated that the structures and apparatuses disclosedherein are merely exemplary for optimizing an imaging sensor, and itshould be appreciated that any structure, apparatus or system foroptimizing a pixel array on an image sensor using a three dimensionalstacking technology and staggering the interconnects between substratesin the stack, which performs functions the same as, or equivalent to,those disclosed herein are intended to fall within the scope of thisdisclosure, including those structures, apparatuses or systems forimaging, which are presently known, or which may become available in thefuture. Anything which functions the same as, or equivalently to, ameans for optimizing a pixel array on an image sensor using a threedimensional stacking technology and staggering the interconnects betweensubstrates in the stack falls within the scope of this disclosure.

Those having ordinary skill in the relevant art will appreciate theadvantages provide by the features of the disclosure. For example, it isa potential feature of the disclosure to provide an optimized pixelarray on an imaging sensor, which is simple in design and manufacture.Another potential feature of the disclosure is to provide such animaging sensor with larger pixels relative to overall size. Anotherpotential feature is to provide an optimized pixel array on an imagesensor using a three dimensional stacking technology and staggering theinterconnects between substrates within the stack.

In the foregoing Detailed Description, various features of thedisclosure are either grouped together in a single embodiment for thepurpose of streamlining the disclosure or are discussed in differentembodiments. This method of disclosure is not to be interpreted asreflecting an intention that the claimed disclosure requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment and variousinventive features disclosed in separate embodiments may be combined toform its own embodiment as claimed more fully below. Thus, the followingclaims are hereby incorporated into this Detailed Description by thisreference, with each claim standing on its own as a separate embodimentof the disclosure.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the disclosure.Numerous modifications and alternative arrangements may be devised bythose skilled in the art without departing from the spirit and scope ofthe disclosure and the appended claims are intended to cover suchmodifications and arrangements. Thus, while the disclosure has beenshown in the drawings and described above with particularity and detail,it will be apparent to those of ordinary skill in the art that numerousmodifications, including, but not limited to, variations in size,materials, shape, form, function and manner of operation, assembly anduse may be made without departing from the principles and concepts setforth herein.

What is claimed is:
 1. An imaging sensor comprising: a plurality ofsubstrates comprising a first substrate and at least one second,subsequent supporting substrate; a pixel array; a plurality ofinterconnects; and a plurality of support circuits; wherein the firstsubstrate of the plurality of substrates comprises the pixel array;wherein the plurality of supporting circuits are disposed on the atleast one second, subsequent supporting substrate that is disposedremotely relative to said first substrate; wherein said plurality ofsupporting circuits are electrically connected to, and in electricalcommunication with, said pixel array via the plurality of interconnectsdisposed between said first substrate and said at least one second,subsequent supporting substrate; wherein said second, subsequentsupporting substrate is disposed behind said pixel array relative to anobject to be imaged; wherein said plurality of interconnects are spacedrelative to one another at a distance that is greater than a pixel pitchof said pixel array.
 2. The imaging sensor of claim 1, wherein saidimaging sensor is backside illuminated.
 3. The imaging sensor of claim1, wherein the plurality of substrates further comprise a plurality ofsecond, subsequent supporting substrates.
 4. The imaging sensor of claim1, wherein said pixel array covers a substantial majority of a surfaceof said first substrate.
 5. The imaging sensor of claim 1, wherein saidpixel array covers more than twenty-five percent of a surface of saidfirst substrate.
 6. The imaging sensor of claim 1, wherein said pixelarray covers more than forty percent of a surface of said firstsubstrate.
 7. The imaging sensor of claim 1, wherein said pixel arraycovers more than seventy percent of a surface of said first substrate.8. The imaging sensor of claim 1, wherein said pixel array covers morethan ninety percent of a surface of said first substrate.
 9. The imagingsensor of claim 1, wherein one of said supporting circuits is an analogto digital converter.
 10. The imaging sensor of claim 1, wherein one ofsaid supporting circuits is an amplifier circuit.
 11. The imaging sensorof claim 1, wherein said at least one second, subsequent supportingsubstrate is aligned in the Z-dimension with said first substrate in astacked configuration.
 12. The imaging sensor of claim 1, wherein saidsecond, subsequent supporting substrate is disposed behind said firstsubstrate and displaced laterally therefrom.
 13. The imaging sensor ofclaim 2, wherein said first substrate is made of primarily siliconmaterial.
 14. The imaging sensor of claim 2, wherein said firstsubstrate is made of primarily of “High-Z” semiconductor material, suchas Cadmium Telluride.
 15. The imaging sensor of claim 2, wherein saidfirst substrate is made of III-V semiconductor materials, such asGallium Arsenide.
 16. The imaging sensor of claim 3, wherein said firstsubstrate and said plurality of second, subsequent supporting substratesare stacked in alignment so that a plurality of communication columnsare formed in a multi-layer stack.
 17. The imaging sensor of claim 1,wherein each of the plurality of interconnects is a bump and comprises abump to bump distance that is greater than two pixels in width.
 18. Theimaging sensor of claim 17, wherein the bump to bump distance is greaterthan four pixels in width.
 19. The imaging sensor of claim 17, whereinthe bump to bump distance is greater than eight pixels in width.
 20. Theimaging sensor of claim 17, wherein the bump pitch is greater than√{square root over ((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}{squareroot over ((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}
 21. The imagingsensor of claim 1, wherein the pixel array is comprised of a pluralityof pixel columns, wherein each pixel column comprises a plurality ofpixels; wherein each of the plurality of pixel columns within the pixelarray is read to a bus, starting from a first column that is read from acommon origin, wherein a second column is read from a first row that isdifferent from the pixel column that was previously read with respect tothe second column and different from the pixel column that is readsubsequent with respect to the second column.
 22. The imaging sensor ofclaim 21, wherein said first row is spaced at least two row positionsaway from the row position of the previously read pixel column and thesubsequently read pixel column.
 23. An imaging sensor comprising: aplurality of substrates comprising a first substrate and at least onesecond, subsequent supporting substrate; a pixel array; a plurality ofinterconnects; and a plurality of supporting circuits; wherein the firstsubstrate of the plurality of substrates comprises the pixel array;wherein the plurality of supporting circuits are disposed on the atleast one second, subsequent supporting substrate that is disposedremotely relative to said first substrate; wherein said plurality ofsupporting circuits are electrically connected to, and in electricalcommunication with, said pixel array via the plurality of interconnectsdisposed between said first substrate and said at least one second,subsequent supporting substrate; wherein said second, subsequentsupporting substrate is disposed behind said pixel array relative to anobject to be imaged; wherein said pixel array covers a majority of afirst surface of said first substrate; wherein said plurality ofinterconnects are spaced relative to one another at a distance that isgreater than a pixel pitch of said pixel array.
 24. The imaging sensorof claim 23, wherein said imaging sensor is backside illuminated. 25.The imaging sensor of claim 23, wherein the plurality of substratesfurther comprise a plurality of second, subsequent supportingsubstrates.
 26. The imaging sensor of claim 23, wherein said pixel arraycovers a substantial majority of a surface of said first substrate. 27.The imaging sensor of claim 23, wherein said pixel array covers morethan fifty-five percent of a surface of said first substrate.
 28. Theimaging sensor of claim 23, wherein said pixel array covers more thansixty percent of a surface of said first substrate.
 29. The imagingsensor of claim 23, wherein said pixel array covers more than seventypercent of a surface of said first substrate.
 30. The imaging sensor ofclaim 23, wherein said pixel array covers more than ninety percent of asurface of said first substrate.
 31. The imaging sensor of claim 23,wherein one of said supporting circuits is an analog to digitalconverter.
 32. The imaging sensor of claim 23, wherein one of saidsupporting circuits is an amplifier circuit.
 33. The imaging sensor ofclaim 23, wherein said at least one second, subsequent supportingsubstrate is aligned in the Z-dimension with said first substrate in astacked configuration.
 34. The imaging sensor of claim 23, wherein saidat least one second, subsequent supporting substrate is disposed behindsaid first substrate and displaced laterally therefrom.
 35. The imagingsensor of claim 24, wherein said first substrate is made of primarilysilicon material.
 36. The imaging sensor of claim 24, wherein said firstsubstrate is made of primarily of “High-Z” semiconductor material, suchas Cadmium Telluride.
 37. The imaging sensor of claim 24, wherein saidfirst substrate is made of III-V semiconductor materials, such asGallium Arsenide.
 38. The imaging sensor of claim 25, wherein said firstsubstrate and said plurality of second, subsequent supporting substratesare stacked in alignment so that a plurality of communication columnsare formed in a multi-layer stack.
 39. The imaging sensor of claim 23,wherein each of the plurality of interconnects is a bump and comprises abump to bump distance that is greater than two pixels in width.
 40. Theimaging sensor of claim 39, wherein the bump to bump distance is greaterthan four pixels in width.
 41. The imaging sensor of claim 39, whereinthe bump to bump distance is greater than eight pixels in width.
 42. Theimaging sensor of claim 39, wherein the bump pitch is greater than√{square root over ((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}{squareroot over ((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}
 43. The imagingsensor of claim 23, wherein the pixel array is comprised of a pluralityof pixel columns, wherein each pixel column comprises a plurality ofpixels; wherein each of the plurality of pixel columns within the pixelarray is read to a bus, starting from a first column that is read from acommon origin, wherein a second column is read from a first row that isdifferent from the pixel column that was previously read with respect tothe second column and different from the pixel column that is readsubsequent with respect to the second column.
 44. The imaging sensor ofclaim 43, wherein said first row is spaced at least two row positionsaway from the row position of the previously read pixel column and thesubsequently read pixel column.
 45. An imaging sensor comprising: aplurality of substrates; a pixel array; and a plurality of supportingcircuits; wherein a first substrate of the plurality of substratescomprises the pixel array; wherein the plurality of supporting circuitsare disposed on at least one subsequent supporting substrate that isdisposed remotely relative to said first substrate; wherein saidplurality of supporting circuits are electrically connected to, and inelectrical communication with, said pixel array; wherein said at leastone subsequent supporting substrates is disposed behind said pixel arrayrelative to an object to be imaged; and wherein said pixel array coversat least forty percent of a first surface of said first substrate;wherein the pixel array of said first substrate electricallycommunicates with the plurality of supporting circuits disposed on saidat least one subsequent supporting substrate through a plurality ofrespective read-buses disposed on each of the plurality of substratesand are electronically connected through interconnects.
 46. The imagingsensor of claim 45, wherein said imaging sensor is backside illuminated.47. The imaging sensor of claim 45, wherein the at least one subsequentsupporting substrate comprises a plurality of subsequent supportingsubstrates.
 48. The imaging sensor of claim 45, wherein said pixel arraycovers a substantial majority of a surface of said first substrate. 49.The imaging sensor of claim 45, wherein said pixel array covers morethan fifty percent of a surface of said first substrate.
 50. The imagingsensor of claim 45, wherein said pixel array covers more than sixtypercent of a surface of said first substrate.
 51. The imaging sensor ofclaim 45, wherein said pixel array covers more than seventy percent of asurface of said first substrate.
 52. The imaging sensor of claim 45,wherein said pixel array covers more than ninety percent of a surface ofsaid first substrate.
 53. The imaging sensor of claim 45, wherein one ofsaid plurality of supporting circuits is an analog to digital converter.54. The imaging sensor of claim 45, wherein one of said supportingcircuits is an amplifier circuit.
 55. The imaging sensor of claim 45,wherein said at least one subsequent supporting substrate is alignedwith said first substrate.
 56. The imaging sensor of claim 45, whereinsaid at least one subsequent supporting substrate is disposed behindsaid first substrate and displaced laterally therefrom.
 57. The imagingsensor of claim 46, wherein said first substrate is made of primarilysilicon material.
 58. The imaging sensor of claim 46, wherein said firstsubstrate is made of primarily of “High-Z” semiconductor material, suchas Cadmium Telluride.
 59. The imaging sensor of claim 46, wherein saidfirst substrate is made of III-V semiconductor materials, such asGallium Arsenide.
 60. The imaging sensor of claim 47, wherein said firstsubstrate and said plurality of subsequent supporting substrates arestacked in alignment so that a plurality of communication columns areformed in a multi-layer stack.
 61. The imaging sensor of claim 45,wherein each of the plurality of interconnects is a bump and comprises abump to bump distance that is greater than two pixels in width.
 62. Theimaging sensor of claim 61, wherein the bump to bump distance is greaterthan four pixels in width.
 63. The imaging sensor of claim 61, whereinthe bump to bump distance is greater than eight pixels in width.
 64. Theimaging sensor of claim 61, wherein the bump pitch is greater than√{square root over ((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}{squareroot over ((N*PixelPitch_(x))²+(M*PixelPitch_(y))²)}
 65. The imagingsensor of claim 45, wherein the pixel array is comprised of a pluralityof pixel columns, wherein each pixel column comprises a plurality ofpixels; wherein each of the plurality of pixel columns within the pixelarray is read to a bus, starting from a first column that is read from acommon origin, wherein a second column is read from a first row that isdifferent from the pixel column that was previously read with respect tothe second column and different from the pixel column that is readsubsequent with respect to the second column.
 66. The imaging sensor ofclaim 65, wherein said first row is spaced at least two row positionsaway from the row position of the previously read pixel column and thesubsequently read pixel column.